Diagnosis and treatment of myofascial pain in small animals (Proceedings)

There are no laboratory or imaging tests available that can confirm the presence of trigger points or myofascial pain disorders, although new studies into the identification of taut bands with magnetic resonance elastography are promising.1 MRI examination of veterinary patients is limited to locating taut bands in skeletal muscles, detecting myofascial restrictions and provoking patient responses to manual pressure. Patient reports of degree of pain and painful referral patterns are not identifiable in animals. Correlating postural deviations, gait and locomotor abnormalities and functional deficits can aid in identifying a pattern of dysfunction. Developing a consistent protocol for palpating for the presence of trigger points and fascial restrictions will enhance the likelihood of locating affected myofascial tissues.

Canine patients likely to develop myofascial pain include athletes or very active dogs, hunting, agility, racing or field trial dogs, geriatric and osteoarthritic patients, those with traumatic injuries or those with neurologic disease or chronic neurologic weakness. It is difficult to find hard data on the prevalence of myofascial disorders, but an Australian study of medical students found that nearly 90% of them had some degree of body pain (primarily in the neck, back and shoulders) of myofascial origin – and those were young people. According to Dr Janet Travell, "Myofascial trigger points are a frequently overlooked and misunderstood source of the distressingly ubiquitous musculoskeletal aches and pains of mankind." It is likely that our patients suffer from a similar degree of pain and dysfunction associated with myofascial dysfunction.

Diagnosis

The diagnosis of myofascial pain in the canine is based on a careful history, observation of locomotor and functional mobility and a thorough and systematic palpation of myofascial tissues. Common owner complaints (none of which are specifically myofascial in origin) include

• Change or decrease in performance

• Lameness (with no discernible joint, tendon or ligamentous pathology)

• Gait deviations such as short striding, base-narrow gait, not tracking straight

• Decreased endurance

• Sudden unwillingness to perform certain activities such as long leash walks, jumping onto the furniture, etc

• Resentful of being touched or brushed.

• Restlessness or difficulty sleeping

A careful gait and functional locomotor examination should be performed, not only looking for lameness, but also evaluating the quality of movement. How willing is the animal to move. Is the movement symmetrical and fluid or asynchronous, shortened and jerky? How does the animal perform on steps, inclines and backing up? Are certain motions restricted in range? Does the animal have adequate endurance or does it fatigue quickly? Can the animal remain stationary for a period of time or does it become restless? Any of these activities may be altered by myofascial pain.

The diagnostic hallmark of myofascial dysfunction is abnormal palpation findings. The presence of nodules and taut bands characterize muscle trigger points. Fascial restrictions will alter tissue texture, resilience and glide. A systematic examination progressing from superficial to deeper tissues should be performed. The animal needs to be relaxed and warm to differentiate tissue tension from voluntary muscle tension.

• Assess thickness and mobility of the skin in relation to the subcutaneous tissues.

• Perform "skin rolling" by lifting and rolling a "wave" of skin.

• Assess the thickness and three-dimensional mobility of the subcutaneous fascia.

• Note patient response to compression of tender fascia.

• Place the muscle to be tested under slight tension. Palpate perpendicular to muscle fibers to locate the taut band.

• Palpate along the taut band to locate the nodule and the area of maximum tenderness.

• Roll the trigger point under the fingers to elicit a local twitch response, an involuntary contraction of the muscle as the taut band is strummed causing a jerk of the body part.

• Apparent tenderness, often reflected by an attempt to bite, is noted.

• Assess the range of motion and flexibility of the affected muscle.

Common trigger points in the canine include but are not limited to: triceps brachii, infraspinatus, latissimus dorsi, peroneus longus, gluteus medius, iliocostalis lumborum, adductor-pectineus, and quadriceps femoris.2

Treatment of myofascial disorders

The treatment of myofascial disorders is aimed at reducing pain, restoring mobility and flexibility, eradicating trigger points and retraining compensatory movement patterns.

Myofascial release

John Barnes, physical therapist and lecturer, defines myofascial release as "the three-dimensional application of sustained pressure and movement into the fascial system in order to eliminate fascial restrictions." Sustained pressure is applied to an area of restriction until a release is felt. The release is due to a proposed lengthening of the fascia and alteration of the extracellular matrix to a more fluid state. These changes would restore flexibility and ease of movement and reduce tension or compression of pain sensitive structures.

Trigger point compression

A number of practitioners have utilized a manual technique to deactivate trigger points. Sustained compression is applied to a painful nodule while the involved muscle is placed under slight tension. Twenty to thirty pounds of pressure trap the offending trigger point; the pressure is held for a minute or more until the nodule softens and tenderness subsides. This technique is also known as ischemic compression, acupressure, shiatsu, or myotherapy.

Dry needling of trigger points (acupuncture)

One of the more effective techniques for deactivating trigger points is to introduce a needle directly into the trigger point. The needle may be either an acupuncture or hypodermic needle. The effectiveness of traditional acupuncture is partially due to its ability to treat trigger points. The "de qi" reaction experienced by acupuncture patients is the aching sensation provoked by penetration of the needle into the trigger point. The effectiveness of needling trigger points is dependent on the specificity of the technique. The needle must penetrate the trigger point and effectiveness is enhanced if a local twitch response is obtained.

Trigger point injection

Trigger points are sometimes injected with corticosteroids and/or local anesthetics. However, studies have demonstrated the effectiveness is due to penetration by the needle and is not improved by injection of medication.

Restoration of flexibility, movement patterns, strength and functional mobility

Manual and needle techniques can diminish pain and normalize tissue function but to optimize patient function these modalities must by followed by additional measures.

• Stretching restores length to shortened muscles and other connective tissues. Over time repetitive movements decrease collagen cross-links, realign fibers along the lines of stress and restore the ability of fibers to slide past one another.

• Neuromuscular reeducation and coordination training restores proper movement patterns and decreases compensatory strategies that may cause recurrence of myofascial disorders.

• Therapeutic exercises for strengthening enable the patient to perform activities of daily living with less effort.

• Functional training encourages the patient to integrates new movement patterns into activities of daily living.

Myofascial pain and dysfunction adversely affect the functional capacity and quality of life of the patient. Incorporating assessments of myofascial tissues into patient examination protocols will ensure that these disorders will be routinely addressed and treated.

References

1. Chen Q, Bensamoun S, Basford JR, Thompson JM, An KN. Identification and quantification of myofascial taut bands with magnetic resonance elastography. Arch Phys Med Rehab 2007 Dec;88(12):1658-61.

2. Janssens LA. Trigger points in 48 dogs with myofascial pain syndromes. Vet Surg 1991; 20(4):274-276.

3. Barnes JF. Myofascial Release: A Comprehensive Evaluatory and Treatment Approach. PT and Rehabilitation Services, Paoli PA; 1990.

4. Travell JG, Simons DG. Myofascial pain and dysfunction: the trigger point manual, Vol I. Baltimore, MD; Williams & Wilkins; 1992

5. Dommerholt J, Mayoral del Moral O, Grobli C. Trigger point dry needling J Man Manip Ther 2006;14(4):E70-E87.